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XXIV. On the Geology and Paleontology of North America, 

 in abstracts of a series of papers recently communicated to 

 the Geological Society of London. Z?y David Dale Owen, 

 M.D.; Charles Lyell, Esq., V.P.G.S., F.R.S.; Gideon 

 Algernon Mantell, LL.D., F.R.S. ; W. C. Redfield, 

 Esq. ; and J. Hamilton Cooper, Esq. 



1. On the Geology of the Western States of North America. By- 

 David Dale Owen, M.D., of Indiana*. 



THE remarks of the author relate chiefly to that part of the west- 

 ern states watered by the rivers Ohio, Wabash, Illinois, Rock, 

 Wisconsin, Cumberland, and Tennessee, lying between 35° and 43° 

 of north latitude, and 81° and 91° of west longitude. It includes the 

 States of Illinois, Indiana, Ohio, Kentucky, Tennessee, and the Du- 

 buque and Mineral Point districts of the territories of Jowa and 

 Wisconsin. The observations recorded are the results of numerous 

 excursions in those provinces, commenced in the year 1834, and 

 continued to the present time by Dr. Owen, sometimes alone, at 

 others accompanied by Dr. Troost and Dr. Locke, the state geologists 

 respectively of Tennessee and Ohio. Though the territory under 

 consideration occupies an area of about half a million of square miles, 

 its geological features are remarkably uniform. With a few partial 

 exceptions its formations belong to the eras of the bituminous coal, 

 the mountain limestone of Europe, and the Silurian rocks of Mur- 

 chison. The exceptions are the superficial deposits which occasion- 

 ally cover these up from view, over considerable districts, and which 

 themselves must be referred to the age of the gigantic mammalia and 

 formations of a still more recent date ; together with a marl and 

 greensand in the western district of Tennessee, corresponding pro- 

 bably to the greensand and other members of the cretaceous group. 



Of the tract described, the formations west of the Tennessee river 

 occupy but a small corner, and the author has had but limited op- 

 portunities of examining them in person. The upper part of this 

 group is an argillaceous marl of a light gray colour ; the lower (of 

 unascertained thickness) a greenish sandy marl. In no instance, as 

 far as known to the author, has either the greensand or marl been 

 discovered east of the Tennessee river. But it exists, according to 

 Dr. Troost, under the superficial soil in most of the countries west 

 of that river, extending probably west and south, into the states of 

 Mississippi and Alabama. Both the marl and greensand are rich in 

 fossils. In the former the most characteristic shell is the Exogyra. 

 Though it is evident, from the character of the fossils imbedded in 

 the marl and greensand beds, that these belong to the cretaceous 

 group, yet hitherto no true chalk has been discovered in Tennessee, 

 nor, so far as I know, in any of the United States. 



In the territory described are two coal-fields of great extent. On 



the west is the great Illinois coal-field, equalling in area the entire 



island of Great Britain, occupying the greater part of Illinois, about 



one-third of Indiana, a north-western strip of Kentucky, and extend- 



* Read before the Geological Society, Nov. 2, 1842. 



